Cleanup: CSS and global styling

In the latest releases, Gitea has fixed a lot of the styling issues we
had manually fixed in the past.

Additionally, the recent style adjustments they did look a lot better
so it is better to remove our custom styling as much as possible, and
follow stock Gitea. Making it easier to upgrade in the future.

* Fix broken styling
* Remove custom font
* Cleanup unused variables
* Add code comments

public/assets/css/theme-bthree-dark.css

@@ -2,16 +2,14 @@
 :root {
   --is-dark-theme: true;
 
-  /* Borders. */
-  --border-radius: .33rem;
-  --border-radius-outer: .28571429rem;
-
   /* Colors. */
   /* Some colors must be set as HEX, due to the monaco-editor no supporting
    * conversion of non-hex colors. https: //github.com/microsoft/monaco-editor/issues/1815 */
   color-scheme: dark;
-  --color-primary: hsl(204deg, 90%, 56%);
-  --color-primary-bg: hsla(204deg, 100%, 36%, .2);
+  --color-primary: hsl(204deg, 90%, 60%);
+  --color-primary-hover: hsl(204deg, 90%, 50%);
+  --color-primary-bg: hsla(204deg, 100%, 36%, .6);
+  --color-primary-text: hsl(204deg, 90%, 72%);
 
   --color-primary-contrast: hsl(0, 0%, 100%);
   --color-primary-dark-1: #14a1ff;
@@ -164,8 +162,6 @@
   --color-code-line-bg-hover: hsl(213, 16%, 16%);
   --color-code-sidebar-bg: hsl(213, 15%, 21%);
 
-  --color-timeline: hsl(220, 10%, 33%);
-
   --color-tooltip-text: #fbfdff;
   --color-tooltip-bg: #000017f0;
 
@@ -177,15 +173,6 @@
   --color-navbar-transparent: hsla(213, 10%, 14%, 0);
   --color-header-bar: hsl(213, 10%, 18%);
 
-  /* Buttons. */
-  --color-button: hsl(213, 14%, 24%);
-  --color-expand-button: hsl(213.9, 12.4%, 26.9%);
-
-  --color-button-basic-border: hsl(213, 14%, 30%);
-  --color-button-basic-bg: hsl(213, 14%, 22%);
-  --color-button-basic-bg: var(--color-light);
-  --color-button-basic-text: var(--color-text);
-
   /* Inputs. */
   --color-input-text: #d6dbe6;
   --color-input-background: #17191c;
@@ -201,7 +188,7 @@
   --color-border: var(--color-secondary-alpha-40);
 
   --color-reaction-bg: hsla(0, 0%, 100%, 0.1);
-  --color-reaction-active-bg: var(--color-primary-alpha-40);
+  --color-reaction-active-bg: var(--color-primary-alpha-30);
 
   --color-small-accent: var(--color-primary-light-5);
   --color-active-line: hsl(53.6, 50.9%, 22%);
@@ -220,142 +207,25 @@
 /* Custom styling of individual elements.
  * Using !important is bad, but unfortunately gitea does it already in _base.less. */
 
-/* Buttons. */
-.ui.basic.button {
-  color: var(--color-button-basic-text);
-  background: var(--color-button-basic-bg);
-  border-color: var(--color-button-basic-border);
-}
-
+/* Primary button. */
 .ui.primary.button,
 .ui.primary.buttons .button {
   background-color: var(--color-primary-bg) !important;
   border-color: var(--color-primary-bg) !important;
-  color: var(--color-primary) !important;
+  color: var(--color-primary-text) !important;
 }
 
+a.ui.primary.label:hover,
 .ui.primary.button:hover,
 .ui.primary.buttons .button:hover {
-  background-color: var(--color-primary) !important;
+  background-color: var(--color-primary-hover) !important;
   color: var(--color-primary-contrast) !important;
 }
 
-/* Small buttons
- * e.g. HTTP/SSH clone buttons in repo homepage. */
-.ui.basic.primary.button,
-.ui.basic.primary.buttons .button {
-  box-shadow: none !important;
-}
-
-.ui.menu,
-.ui.vertical.menu {
-  border-color: var(--color-secondary-alpha-30) !important;
-}
-
-/* Vertical menu.
- * Used in: /issues */
-.ui.vertical.menu {
-  padding: var(--spacer-1);
-  border-radius: var(--border-radius);
-}
-
-/* Vertical menu: active item.
- * Gitea adds a "primary" class to what would be the active item. */
-.ui.vertical.menu > .item.primary {
-  background-color: var(--color-active) !important;
-  box-shadow: none !important;
-}
-
-/* Dropdown menus.
- * e.g. user menu. */
-.ui.dropdown .menu {
-  border-radius: var(--border-radius) !important;
-  box-shadow: var(--box-shadow-dropdown-menu) !important;
-}
-
-/* Replace gitea's hardcoded border-radius with variables. */
-.ui.compact.menu {
-  border-radius: var(--border-radius-outer);
-}
-
-.ui.compact.menu>.item:first-child {
-  border-radius: var(--border-radius) 0 0 var(--border-radius);
-}
-
-.ui.compact.menu>.item:last-child {
-  border-radius: 0 var(--border-radius) var(--border-radius) 0;
-}
-
-.ui.menu.new-menu {
-  border-color: var(--color-secondary-alpha-50) !important;
-}
-
-/* Top navigation bar.
- * e.g. Issues, Pull Requests, etc. */
-.ui.menu.bar {
-  border-color: var(--color-border);
-}
-
-.ui.menu .item>.label {
-  color: var(--color-label-text);
-}
-
-.ui.tabular.menu {
-  border-color: var(--color-border);
-}
-
-.ui.breadcrumb a {
-  color: var(--color-text);
-}
-
-/* Cards. */
-.ui.cards>.card .meta,
-.ui.card .meta {
-  color: var(--color-text-dark-2);
-}
-
-.ui.card.card-with-icon .icon svg {
-  margin: 0 var(--spacer) 0 0;
-  width: 50px;
-  opacity: .7;
-}
-
-/* Users/Organizations list. */
-/* Fix alignment issue since */
-.ui.user.list img.avatar,
-.ui.user.list img.avatar+.content {
-  display: inline-block;
-}
-
-.ui.user.list img.avatar {
-  position: relative;
-  top: 3px;
-  vertical-align: initial !important;
-}
-
-.ui.user.list .content {
-  margin-left: var(--spacer-2);
-  width: auto;
-}
-
-.ui.user.list .content .description .svg {
-  margin-right: var(--spacer-1);
-  position: relative;
-  top: 2px;
-}
-
-.issue.list>.item+.item {
-  border-color: var(--color-border);
-}
-
-/* Divider. */
-.ui.divider:not(.vertical, .horizontal) {
-  border-top-color: var(--color-border) !important;
-}
-
-/* Homepage. */
-.home a {
-  color: var(--color-accent);
+.ui.primary.label {
+  background-color: var(--color-primary-bg) !important;
+  border-color: var(--color-primary-bg) !important;
+  color: var(--color-primary) !important;
 }
 
 /* (from arc-green)